Considerable need exists for the ability to quantitate the thermal effects of electromagnetically-induced hyperthermia prior to the application of such treatment. The results of in vivo dielectric property measurements performed over a wide frequency range (1 MHz-6.0 GHz) on normal and neoplastic tissues can be used to aid in systematically selecting the frequency or frequencies where electromagnetic (EM) power is absorbed maximally by the tumor and minimally by normal tissues. Current research in this laboratory has shown that the frequencies of maximum energy absorption by tumors in animals are different tumor types. By determining the dielectric properties (and from those properties, the power absorption and thermal rise) of diseased and normal tissue, it should be possible to plan hyperthermia treatment regimens which would be most effective without damaging normal tissues in a manner similar to that now used for planning radiotherapy treatments. Such an ability could be extremely useful for the difficult case of deep-seated tumor treatment. The principal aims of the proposed research are (1) to provide significant additional dielectric property information on living normal and neoplastic human tissues using the in vivo probe measurement technique developed at Georgia Tech, (2) to assess the complexities involved with using these data for specifically quantitating EM power absorption and with utilizing predicted power absorption differences and measured blood flow in thermal models for predicting differential thermal rise for normal and neoplastic tissues, (3) to utilize these dielectric property data for determining relative differences in EM power absorption by normal and neoplstic tissues as a function of frequency, and (4) to experimentally verify predicted thermal differentials for the case of a single animal tumor model and assess potential problems involved with extending these types of analyses to the human case.